Ultra-Bright X-rays Beams from Laser Plasma Accelerators

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Ultra-Bright X-rays Beams
from Laser Plasma Accelerators
Victor Malka
Laboratoire d’Optique Appliquée
ENSTA ParisTech – Ecole Polytechnique – CNRS
PALAISEAU, France
[email protected]
Conference on High Intensity Laser and Attosecond Science in Israel, Tel-Aviv, December 2-4 (2013)
http://loa.ensta.fr/
mercredi 4 décembre 13
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X rays source with Laser Plasma accelerators
a
e
n
i
l
n 003
o
N 2
n
o
s
m
o
h
T
r
1 keV
Xuv
t
a
i
d
a
r
n
o
r
t
a
t 004
e
B 2
10 keV
X
n
o
i
n
o
t
p 1
m 01
o
2
C
100 keV
a
c
s
e
t
t
g
n
ri
h
a
r
t
ss
m 10
e
20
Br
1 MeV
ɣ
g
n
lu
10 MeV
Common features: Collimated beams (mrad)
Femtosecond duration (few fs)
Micron source size
High peak brightness (>1020 ph/s/mm2/mrad2)
- naturally synchronized (ideal for pump-probe experiments)
- compacts and useful for small scale laboratories
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Moving charge radiation
Velocity
Acceleration
n unit vector in the observation direction
Radiated energy
.
Rc
β
Electron
β
To efficiently produce X-ray radiation we need relativistic electrons undergoing oscillations
(synchrotron radiation)
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The laser wakefield
F=-∇I
V. Malka et al., Science 298, 1596 (2002)
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X rays Source with Laser Plasma Accelerators : Outline
LPA
๏Betatron radiation produced in
Participants :
- Experimental characterization
- Electron-X rays beams correlations
- Diagnostics for LPA
- Single shot contrast imaging
๏All optical Compton gamma rays source
- Principle
- Experimental results
๏Bremsstrahlung gamma rays source
- Principle
Acknowledgements :
๏Conclusion and perspectives
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LPA
Participants :
- Principle
๏Bremstralhung gamma rays source
- Principle
Acknowledgements :
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Laser “Salle Jaune”
Ti:sapphire CPA laser
1.0 J / 30 fs - 10 Hz
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Betatron radiation properties
Transverse force
Longitudinal Force
Betatron oscillation
properties:
p
u
=
2
K = r kp
⇠ 100 MeV
p
p
/2
r ⇠ 1 µm
ne ⇠ 1019 cm
⇠ 200 µm
K⇠5
u
3
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Spatial distribution of the emitted radiation
ϑY (mrad)
Detector
He gas jet
ϑx (mrad)
Scaling law
Cone aperture:
ϑx = K/γ
∼50 mrad for K = 10 and 100 Mev electrons
Cone width:
ϑY = 1/γ
∼5 mrad
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A more precise source size estimation
Experimental profiles
Calculated profiles
Electron orbits
60
θy (mrad)
40
20
0
-20
-40
-60
60
θy (mrad)
40
20
0
-20
-40
-60
-60
-20
-40
0
20
θx (mrad)
40
60
-60
-20
-40
0
20
40
60
θx (mrad)
K. Ta Phuoc et al, PRL 2006
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A more precise source size estimation
Experimental profiles
Calculated profiles
Electron orbits
60
θy (mrad)
40
20
0
-20
3µ
m
3µ
m
1.5 µm
-40
-60
60
θy (mrad)
40
20
0
-20
-40
-60
-60
-20
-40
0
20
θx (mrad)
40
60
-60
-20
-40
0
20
40
60
θx (mrad)
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Betatron signal variation with density
experimental data
3 PIC simulation
A. Rousse et al., Phys. Rev. Lett., 93, 135005 (2004)
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Femtosecond x-ray diffraction: Non thermal melting (InSb)
CD
yC
ra
X-
Pump
Ultrafast phase transition can be measured
with tens fs resolution - limited by shot to
shot fluctuations of the source
Normalized diffracted x-ray
ad
Le
Probe
Experiment
Delay Δt (ps)
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InSb sample
Estimation of the x-ray pulse duration: results
x-ray
NormalizedI(diffracted
Δt)
Experiment
τ = 100 fs
τ = 500 fs
τ = 1000 fs
Delay Δt (ps)
τ < 1 ps
Ta Phuoc
K. Ta Phuoc et al., PoPK.
2007
●
Best fit for τ < 100 fs
et al., Phys. of Plasmas, 14, 080701 (2007)
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Colliding Laser plasma accelerator and Betatron
In the relativistic regime, electrons oscillate at a speed close to
eA
the speed of light :
a0 =
me c
Pump beam Injec2on beam - The Laplace force is non negligible
and electron dynamic is non linear.
- The ponderomotive force
excites the plasma wave.
~ 20
ra
- T h i s e x c i t a t i o n i s e f fi c i e n t
if : ⌧ ⇠ ⇡!p. 1
Wakefield - The excited plasma wave amplitude is
large and has a non linear behavior
if : a0 & 1 .
J. Faure et al., Nature 444, 737 (2006)
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eA
a0 =
me c
Pump beam Injec2on beam Beatwave - The Laplace force is non negligible
~ 20
ra
if : ⌧ ⇠ ⇡!p. 1
Wakefield Injec&on phase - The excited plasma wave amplitude is
if : a0 & 1 .
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eA
a0 =
me c
Pump beam Trapped electrons Injec2on beam Beatwave - The Laplace force is non negligible
~ 20
ra
if : ⌧ ⇠ ⇡!p. 1
Wakefield Accelera&on phase Accelera&on phase Injec&on phase - The excited plasma wave amplitude is
if : a0 & 1 .
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Electron and X ray correlation (LOA experiments)
Faisceau
Probe
pulse
d’ombroscopie
shadowgraphy
Laser pulse
Impulsion
laser
0.1
0.1 JJ/30fs
/ 35 fs
Filtre
Be
Be filter
X
rays
Rayons X
He gasJetjetde
Aimant
magnet
gaz He
e-
Miroir
torique
toroidal
mirror
Raw electron spectra
D
CC
Ecran
Scintillator
scintillateur
Screen
CCD X
Laser pulse
Impulsion
laser
0.9J J/30fs
0.9
/ 35 fs
transmission
Réseau en
grating
transmission
Collision angle :135°
ne = 8×1018 cm-3
CCD
Optical injection: more stable and higher
e-beam quality
E-beam energy is controlled by changing
the delay line
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Electron and X ray correlation (LOA experiments)
Thanks to the colliding laser pulses scheme, clear correlations between
electron beam energy and betatron X ray distribution are observed
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Electron and X ray correlation : comparison
↵ = 1 and
et
The best agreement is obtained for :
q
= 2kB T? /(↵m!p2 ) = 0.23 µm at
à E = 200 MeV
or ↵ = 0.23 µm)
(ou
S. Corde et al., Phys. Rev. Lett.107, 225003 (2011)
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Electron & Xray correlation: divergence and charge
Divergence (FWHM) the X betatron signal with the electron beam energy:
Collision position z=0.1mm
(a)
✓ (mrad)
23.5 mrad
14
0
14
14
0
14
14
0
14
Collision position z=-0.5mm
Collision position z=-0.2mm
(b)
(c)
19.5 mrad
16.5 mrad
(a)
(b)
(c)
50
100
E (MeV)
200
1
Linear dependency of the X betatron signal with
the electron beam charge (for a fixed electron
beam energy at ~220 MeV)
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X ray Phase Contrast Radiography
X source
σ
object
R
● Absorption contrast
Det
ecto
r
● Phase contrast
Contrast is due to the absorption
difference in the object
Interferences can reveal object
interfaces
It works only with object with
important absorption difference
Biological objects have phase
contrast 1000 times higher than
absorption contrast
It requires a very high spatial
coherence (10’s microns) : d = λR/2πσ
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X ray Phase Contrast Radiography: Experiments
Be
window
Fenêtres
Be
Betatron X ray radiation
Rayonnement X bétatron
Parabole
horsparabola
axe
Off axis
X ray diagnostic
Filtre
AlAl
filter
deviatedd’électrons
electron beam
Faisceau
dévié
Echantillon
imager
object to àimage
Parameters of the source :
- Ec = 12.3 keV
- 2.2×108 photons/0.1%BW/sr/shot at 10 keV
- N = 109 photons in 28 mrad (FWHM) divergence beam
S. Fourmaux et al., Opt. Lett. 36, 2426 (2011)
CCD X
f3s0 fs
0
3
J ./5 J /
5
.
2er 2
m
s
a
a
bioen l
r
e
s
la puls
m
I
JetHe
degas
gazjet
He dipole magnet
Aimant
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X ray Phase Contrast Radiography: Results
Bee contrast image :
- Contrast of 0.68 in single shot.
- Very tiny details can be observed in single shot that disappear in multi shots.
1 shot
13 shots
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LPA
Participants :
- Principle
- Principle
Acknowledgements :
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Inverse Compton Scattering
Doppler upshift : high energy photons with modest electrons energy : ωx=4γ2ω0
For example : 20 MeV electrons can produce 10 keV photons
200 MeV electrons can produce 1 MeV photons
The number of photons depends on the electron charge Ne and a02 : Nx
∝ a02 x Ne
Duration (fs), source size (μm) = electron bunch length and electron beam size
Spectral bandwidth : ΔE/E
∝ 2Δγ/γ, γ2Δθ2
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Inverse Compton Scattering : New scheme
50 TW / 30 fs
laser
X rays
solid foil
He gas jet
Foil, blade
Back reflected laser pulse
Plasma mirror
A single laser pulse
A plasma mirror reflects the laser beam
The back reflected laser collides with the
accelerated electrons
High energy
X ray beam
No alignement : the laser and the electron
beams naturally overlap
Save the laser energy !
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Inverse Compton Scattering : Experimental set-up
He gas jet
Magnet
X rays
50 TW / 30 fs
laser
Foil, blade
Electron spectra
Scintillator screen
50 micron Al foil
electrons
X ray beam profile
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CCD
Inverse Compton Scattering : Experimental results
Compton scattering
● The foil must be placed at the right to maximize a0 and the electrons energy
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Compton scattering
electron energy decreases
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Compton scattering
electron energy decreases
laser intensity decreases
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Inverse Compton Scattering : Compton Spectra
Al 2.1 mm
Cu 0.5 mm
Cu 4 mm
B
Cu 1 mm
Cu 8 mm
Cu 2 mm
Cu 12 mm
A
calculation with test particle : a0=1.2
● About 108 ph/shot, a few 104 ph/shot/0.1%BW@100 keV
● Broad electron spectrum => broad X ray spectra
● Brigthness: 1021 ph/s/mm2/mrad2/0.1%BW @100 keV
K. Ta Phuoc et al., Nature Photonics, May 2012
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Inverse Compton Scattering : Source size
5 mm
● In this image the resolution is limited
by the detector and the small magnification
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LPA
Participants :
- Principle
- Principle
Acknowledgements :
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Some examples of applications : radiography
Non destructive dense matter inspection
High resolution radiography of dense object with a low divergence, point-like electron source
In collaboration with CEA/DAM
A. King et al., MRS Bulletin 94, 8 (2006)
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Some examples of applications : radiography results
400 μm γ source size
Cut of the object in 3D
2005
Spherical hollow object in tungsten
with sinusoidal structures etched
on the inner part.
50 μm γ source size
2010
Y. Glinec et al., PRL 94, 025003 (2005)
A. Ben-Ismail et al., Nucl. Instr. and Meth. A 629 (2010)
A. Ben-Ismail et al., App. Phys. Lett. 98, 264101 (2011)
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Application to Non Destructive Control
Artistic view of non destructive
control machine
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LPA
Participants :
- Principle
- Principle
Acknowledgements :
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Conclusion
Laser plasma accelerators can deliver high quality X ray beams
(i) Betatron : 108-109 ph/shot - fs - micron - 10’s keV - 10’s mrad
(ii) Compton : 108-109 ph/shot - fs - micron - 100’s keV
104 photons/shot/0.1% BW @ 100 keV
(10 000 brighter than existing sources)
(iii) Bremsstrahlung:105-106 ph/shot - ps - 10’s micron - 10’s MeV
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Conclusion and Perspectives
- Betatron radiation:
Fully characterized, used for first applications
↦ High repetition rate keV source
↦ High energy radiation: 100s keV
- All optically driven Compton x-ray source:
First demonstration in the hard x-ray range
↦ Produce x-ray beams at higher repetition rates (compact lasers).
↦ Produce tunable monochromatic fs x-ray/gamma-ray beams.
- Applications:
Ultrafast x-ray absorption, diffraction experiments, radiography
↦ keep developing these applications
↦ Applications for ICF under consideration
Femtosecond X-rays from laser plasma accelerators
S. Corde et al., Review of Modern Physics, 85, 1, 2013
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Perspectives
Near future developments
Produce a nearly monochromatic radiation source:
from a few keV to a few MeV
To do so we will use monoenergetic electrons produced from a laser plasma accelerator
Expected x-ray spectra
Photons / shot / eV / mrad2
50 MeV
70 MeV
30
90 MeV
110 MeV
20
130 MeV
10
0
100
200
300
400
500
Energy (keV)
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Collaborators
Sebastien Corde, Kim Ta Phuoc, Cédric Thaury, Agustin Lifschitz,
Romuald Fitour, Antoine Rousse, Stephane Sebban
Laboratoire d’Optique Appliquée, ENSTA ParisTech – Ecole Polytechnique –
CNRS, Palaiseau, France
Sylvain Fourmaux, Jean-Claude Kieffer
INRS-EMT - Advanced Laser Light Source, Quebec, Canada
Xavier Davoine, Erik Lefebvre
CEA/DAM/DIF, Arpajon, France
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Ultra-Bright X-rays Beams from Laser Plasma Accelerators

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